1. Field of the Invention
The present invention relates to a circuit for suddenly stopping a brushless micromotor used for a dental handpiece for example.
2. Prior Art
The conventional sudden stop circuit for a brushless micromotor has a construction in which plural motor coils are short-circuited by relays or switches depending on a motor stop signal or has a construction in which its rotor is suddenly stopped by applying a rotor position locking voltage. In the former case, a large PC board space is necessary for the relays or switches. In the latter case, the rotor rotates up to 180 degrees when power is turned on. The rotor cannot be suddenly stopped since a current flows through a coil while power is turned on. In addition, the rotor cannot be released from locking after it is locked.